OTULINL (FAM105A) is a pseudodeubiquitinase of the OTU family that lacks catalytic deubiquitinase activity despite structural homology to active DUBs 1. Crystal structure analysis reveals critical deficiencies in both the active site and substrate-binding regions that prevent ubiquitin cleavage across all linkage types 1. Unlike its catalytically active paralog OTULIN, OTULINL cannot bind ubiquitin or process ubiquitin chains 1. Instead, OTULINL functions as a protein interaction scaffold, localizing to the endoplasmic reticulum (ER) and nuclear envelope where it associates with proteins involved in membrane trafficking, vesicular transport, and ER/Golgi functions 1. Recent genome-wide association studies identified OTULINL as a novel genetic locus associated with renin-angiotensin-aldosterone system inhibitor-induced angioedema, a serious adverse drug reaction with significant racial disparities 2. This discovery suggests OTULINL may play a role in bradykinin-related pathways implicated in angioedema pathogenesis 2. The functional role of OTULINL likely depends on protein-protein interactions rather than enzymatic activity, reflecting an emerging class of pseudoenzymes with scaffold functions in cellular homeostasis.